An industrial automation system usually comprises a multiplicity of automation devices networked to one another via an industrial communication network and, within the scope of production or process automation, is used to control or regulate installations, machines or devices. On account of time-critical boundary conditions in technical systems automated using industrial automation systems, real-time communication protocols, such as Profinet, Profibus or real-time Ethernet, are predominantly used in industrial communication networks for communication between automation devices.
Interruptions in communication connections between computer units of an industrial automation system or automation devices may result in undesirable or unnecessary repetition of the transmission of a service request. This causes additional utilization of communication connections of the industrial automation system, which may result in further system faults or errors. In addition, untransmitted messages or incompletely transmitted messages may prevent an industrial automation system from changing to or remaining in a safe operating state, for example. This may finally result in failure of a complete production installation and costly production downtime. A particular problem regularly results in industrial automation systems from message traffic with a comparatively large number of, but relatively short, messages, thus intensifying the above problems.
WO 2008/119649 A1 discloses a method for reconfiguring a packet-switched communication network comprising a first subnetwork and a second subnetwork. Whereas a first network protocol is used in the first subnetwork, a second network protocol different from the first network protocol is used in the second subnetwork. Both subnetworks are connected to one another over at least three redundant data links, only one of which is respectively activated for the purpose of interchanging useful data. Here, a master data link is activated in a preset manner, while at least two slave data links are deactivated in a preset manner. Failure of the master data link or a slave data link is monitored by a master bridge of the second subnetwork, which master bridge is connected to the master data link. In the event of such failure, the master bridge generates a first data packet and transmits this first data packet to a slave bridge of the second subnetwork, which slave bridge is connected to a slave data link. The slave bridge is selected by the master bridge according to a predefinable selection rule. The first data packet is then processed by the selected slave bridge. The first data packet comprises logical information that is used to at least partially execute the first network protocol on a port of the slave bridge connected to the slave data link and to activate the slave data link using the first network protocol executed on the port of the slave bridge.
EP 2 343 857 A1 describes a network node for a communication network comprising a first subnetwork and a second subnetwork connected to the latter. Whereas a spanning tree protocol is used in the first subnetwork, a second protocol that differs from the protocol of the first subnetwork is used in the second subnetwork. The network node is set up as an element for the second subnetwork and is designed for communication inside the second subnetwork. In addition, the network node is designed and set up as a spanning tree main node for monitoring and controlling the second subnetwork by a spanning tree functionality. The second subnetwork can therefore be treated as a virtual network node by the spanning tree protocol used in the first subnetwork by virtue of the network node, as the spanning tree main node, applying a spanning tree protocol for other network nodes of the second subnetwork.
WO 2010/105828 A1 discloses a method for operating a communication network which has redundancy properties and has a ring network topology. Inside the communication network, the data ports of communication devices are connected to one another via data lines and the communication devices interchange control data and useful data via the data lines based on communication protocols. In order to avoid endless circulation of messages in meshes of the communication network, the communication protocols are used to prevent transmission of messages via selected data ports of individual communication devices, with the exception of messages for controlling or monitoring media redundancy. Two different communication protocols are used in a parallel manner in the communication devices inside the communication network. Parallel use of the different communication protocols is achieved, for example, by allocating control of data ports to be blocked to an individual communication protocol. Alternatively, parameters may be selected for the communication protocols such that a first communication protocol does not block any connections that are considered to be active in accordance with a second communication protocol.